package main

import (
    "fmt"
    "os"
    "strings"
)

// A Command is an implementation of a go command
// like go build or go fix.
type Command struct {
    // Run runs the command.
    // The args are the arguments after the command name.
    Run func(cmd *Command, args []string)

    // UsageLine is the one-line usage message.
    // The first word in the line is taken to be the command name.
    UsageLine string

    // Short is the short description shown in the 'go help' output.
    Short string

    // Long is the long message shown in the 'go help <this-command>' output.
    Long string

    // Flag is a set of flags specific to this command.
    Flags map[string]bool
}

// Name returns the command's name: the first word in the usage line.
func (c *Command) Name() string {
    name := c.UsageLine
    i := strings.Index(name, " ")
    if i >= 0 {
        name = name[:i]
    }
    return name
}

func (c *Command) Usage() {
    fmt.Fprintf(os.Stderr, "usage: %s\n\n", c.UsageLine)
    fmt.Fprintf(os.Stderr, "%s\n", strings.TrimSpace(c.Long))
    os.Exit(2)
}

// Runnable reports whether the command can be run; otherwise
// it is a documentation pseudo-command such as importpath.
func (c *Command) Runnable() bool {
    return c.Run != nil
}

// checkFlags checks if the flag exists with correct format.
func checkFlags(flags map[string]bool, args []string, print func(string)) int {
    num := 0 // Number of valid flags, use to cut out.
    for i, f := range args {
        // Check flag prefix '-'.
        if !strings.HasPrefix(f, "-") {
            // Not a flag, finish check process.
            break
        }

        // Check if it a valid flag.
        if v, ok := flags[f]; ok {
            flags[f] = !v
            if !v {
                print(f)
            } else {
                fmt.Println("DISABLE: " + f)
            }
        } else {
            fmt.Printf("[ERRO] Unknown flag: %s.\n", f)
            return -1
        }
        num = i + 1
    }

    return num
}
